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2bbde9d9a9
Datastore has a non-zero chance of failing on reads. A map-reduce with too many failures will eventually give up. As a result, any map-reduce that goes over a large number of datastore entities is almost guaranteed to fail. Since we expect to have a large number of EppResources, we make sure to wrap all datastore reads with some retrying mechanism to reduce the number of transient failures that propagate to Map-Reduce. This feature already existed for CommitLogManifestReader, we refactor the code to use the same retrying mechanism in EppResource readers. Also removed the transactNew around the reads because looking at the source - it doesn't actually do anything we need (doesn't retry on any failure other than concurrency failure) ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=190633281
77 lines
2.9 KiB
Java
77 lines
2.9 KiB
Java
// Copyright 2017 The Nomulus Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package google.registry.mapreduce.inputs;
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import static google.registry.model.ofy.ObjectifyService.ofy;
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import com.google.appengine.tools.mapreduce.InputReader;
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import com.google.common.collect.ImmutableSet;
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import com.googlecode.objectify.Key;
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import google.registry.model.EppResource;
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import google.registry.model.index.EppResourceIndex;
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import google.registry.model.index.EppResourceIndexBucket;
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import java.util.NoSuchElementException;
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/** Reader that maps over {@link EppResourceIndex} and returns resources. */
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class EppResourceEntityReader<R extends EppResource> extends EppResourceBaseReader<R> {
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private static final long serialVersionUID = -8042933349899971801L;
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/**
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* The resource classes to postfilter for.
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*
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* <p>This can be {@link EppResource} or any descendant classes, regardless of whether those
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* classes map directly to a kind in Datastore, with the restriction that none of the classes
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* is a supertype of any of the others.
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*/
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private final ImmutableSet<Class<? extends R>> resourceClasses;
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public EppResourceEntityReader(
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Key<EppResourceIndexBucket> bucketKey,
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ImmutableSet<Class<? extends R>> resourceClasses) {
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super(
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bucketKey,
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ONE_MB * 2, // Estimate 2MB of memory for this reader, since it loads a (max 1MB) entity.
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varargsToKinds(resourceClasses));
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this.resourceClasses = resourceClasses;
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}
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/**
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* Called for each map invocation.
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*
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* @throws NoSuchElementException if there are no more elements, as specified in the
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* {@link InputReader#next} Javadoc.
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*/
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@Override
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public R next() throws NoSuchElementException {
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// Loop until we find a value, or nextQueryResult() throws a NoSuchElementException.
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while (true) {
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Key<? extends EppResource> key = nextQueryResult().getKey();
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EppResource resource = ofy().load().key(key).now();
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if (resource == null) {
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logger.severefmt("EppResourceIndex key %s points at a missing resource", key);
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continue;
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}
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// Postfilter to distinguish polymorphic types (e.g. DomainBase and DomainResource).
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for (Class<? extends R> resourceClass : resourceClasses) {
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if (resourceClass.isAssignableFrom(resource.getClass())) {
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@SuppressWarnings("unchecked")
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R r = (R) resource;
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return r;
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}
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}
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}
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}
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}
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